Intravascular filters such as embolic protection filters are generally placed within a body lumen, such as an artery or vein, downstream of a therapeutic site to filter embolic debris from the blood stream. Examples of therapeutic procedures employing such filters include angioplasty, atherectomy, thrombectomy and stent placement. In a typical procedure, a guidewire is transluminally inserted into the patient and placed across the site of the lesion. An embolic protection filter is then advanced along the guidewire and placed distal the lesion. A therapeutic device such as a dilatation or atherectomy catheter is then advanced along the guidewire and placed proximal the therapeutic site to perform the procedure. The therapeutic device is then engaged, forcing the embolic debris to become dislodged from the walls of the vessel and flow downstream towards the distal vasculature, where it is collected and stored by the filter.
There are numerous types of interventional devices adapted to collect embolic debris released into the blood stream during a therapeutic procedure. Typically, these devices contain a mesh or microporous membrane attached to a support structure having struts, wires, and/or ribs that support the filter within a blood vessel when deployed. Generally, the shape of these filters include a proximal mouth or opening that tapers distally to a closed end portion. Examples of such configurations include baskets, parachutes, or sleeves. In a typical application, embolic debris enters the proximal end of the device, and flows distally where it is stored at the closed end portion of the filter.
Depending on the amount of embolic debris dislodged from the vessel wall, the embolic protection filter may become partially or fully occluded throughout the course of the therapeutic procedure. As a result of the buildup of embolic debris within the filter, the perfusion of blood through the filter diminishes over time.